A. Field of the Invention
This invention relates to the field of telecommunications and more particularly to communication access devices that allow for incoming and outgoing data communications to be transmitted between a multiplexed digital telephone line and a computer network such as a local or wide area network.
B. Description of Related Art and Advantages of the Invention
Computer networks have been typically linked to the public switched telephone network using various types of connection equipment, such as channel banks, PBX equipment, and gateway devices. Several references that describe such network access devices or related systems include the patents to Thomas, U.S. Pat. No. 4,796,292; Miller et al., U.S. Pat. No. 5,402,474; Ogasawara et al., U.S. Pat. No. 5,220,560. Other references of interest include the patents to Hunt et al., U.S. Pat. No. 5,361,259; Flohr, U.S. Pat. No. 5,374,952 and Yoshida, U.S. Pat. No. 5,247,516. The patent to Davis, U.S. Pat. No. 4,991,169, describes an all-digital DSP approach for interfacing between a telephone line and a host computer system.
In the past, network access devices such as channel banks and PBXs have been viewed simply as access devices for the host computers on the network. The signal processing and computational capabilities built into such devices were primarily devoted to A/D and modem signal conversions for the incoming and outgoing calls, protocol processing necessary to interface with the local area network and perform routing functions, and processing associated with multiplexing and demultiplexing functions to receive or transmit calls to time slots on a time division multiplexed carrier system, such as T1.
The present invention represents a significant departure from the prior art approach to the role and limited functionality of communication access devices per se. Whereas in the prior art communication access devices have been designed to perform a limited role in terms of call processing and routing, with the ultimate destination for the calls being one or more host computers on the local area network, we have developed a communications server chassis that, in addition to providing the network access functions of an integrated communications router, also includes a general purpose computing platform. The platform runs a commercially available stand alone or shareware operating system such as Windows.RTM. NT from Microsoft Corporation. The software running on the computing platform may perform, for example, network management, remote access, intranet web page, and other functions.
A communication access device with the integral general purpose computing platform, as described herein, provides a substantial advancement in the features and capabilities of a communication access device. For example, in an embodiment in which the communication access device is connected to the network, improved remote access service may be achieved since the general purpose computing platform can route certain calls to the LAN while terminating other calls, such as those calls that require access to information that is stored locally in the memory in the general purpose computing platform. Additionally, the general purpose computing platform may provide enhanced network management service efficiently controlling the flow of calls between the access device and the network. The general purpose computing platform may also provide protocol proxy service and authentication services.
The installation of the general purpose computing platform in the communications access device allows for calls from remote users that dial into the chassis to be terminated in the general purpose computing platform. The host computer on the local area network that would be the endpoint of an incoming call in the prior art, is, in both reality and in effect, placed into the communication access device itself. Moreover, since the communication access device has the capability of handling a large number of incoming calls at the same time, due to the call processing and signal conversion circuitry included in the chassis and described below, the communication access device can perform both communication access and information access functionality at the same time in the same physical chassis. This feature can result in improved network security since it enables the communication access device to be physically and electrically isolated from the local area network, since calls are terminated at the communications chassis. This is all accomplished in a manner completely transparent to the remote user.
These and many other features and advantages of the invention will become more apparent from the following detailed description of preferred embodiments of the invention.